Răspuns :
(a+b+c)/3=6
a+b+c=6x3
a+b+c=18
c=(a+b)/4
a+b+(a+b)/4=18
(4a+4b+a+b)/4=18
5a+5b=18x4
5(a+b)=72
a+b=72/5
c=(a+b)/4=(72/5)/4=72/(5x4)=72/20=simplif cu 4=18/5
c=3,6
a+b+c=6x3
a+b+c=18
c=(a+b)/4
a+b+(a+b)/4=18
(4a+4b+a+b)/4=18
5a+5b=18x4
5(a+b)=72
a+b=72/5
c=(a+b)/4=(72/5)/4=72/(5x4)=72/20=simplif cu 4=18/5
c=3,6